There are in operation, at least on a limited scale today, two basic types of solar energy collecting systems; a so-called flat-plate collector comprised of a plate of glass and an energy absorbing surface spaced therebeneath, i.e., away from the sun. At the back of the absorbing surface the heat exchange media in either gas or liquid form is circulated to exchange the heat of the sun to the exchange media. Another type is the double-walled glass tubular collector in which a glass outer tube is sealed to a spaced inner tube and the space evacuated. The inner tube has an energy absorbing coating over its exposed surface and the heat exchange media is circulated on the inside of the inner tube to absorb solar heat collected by the inner tube. Several of the tubular collectors are connected into a manifold system which furnishes the media to the tubes and transfers the heated media for storage or use of the sun's energy that is absorbed in the apparatus. One of the drawbacks of the tubular collector, as compared with the flat plate collector, is the difficulty with which many tubes of a collector assembly may be connected to a manifold and function as a unit.